Hybrid camera arrangement

ABSTRACT

A &#34;hybrid&#34; exposure control system for a photographic camera apparatus controls exposure in response to both the firing of a quench strobe at an appropriate size aperture corresponding to the determined camera-to-subject distance and to the subsequent quenching of the strobe in response to the detection and integration of reflected strobe light from the scene in correspondence with the scene light admitted to the film plane. An increased degree of exposure correction can thus be made possible since a slight error in determining the camera-to-subject range can be compensated by the detection and integration of reflected strobe light to provide a flash quenching signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a "hybrid" exposure control systemfor a photographic camera apparatus and, more particularly, to a"hybrid" exposure control system for a photographic camera apparatusutilizing a quench strobe.

2. Description of the Prior Art

So-called "hybrid" exposure control systems are well known in the artand generally operate to control exposure in response to both firing aflash lamp at an appropriate aperture size calculated to generallycorrespond to the determined camera-to-subject distance in accordancewith the inverse square law of light and the subsequent detection andintegration of reflected artificial illumination from the scene toprovide a shutter blade closing command signal. This makes possible anincreased degree of exposure correction since a slight error in thedetermination of camera-to-subject range resulting in a correspondingerror in the aperture size at which the flash lamp is fired can beeasily compensated by the detection and integration of the reflectedartificial illumination to provide the shutter blade closing commandsignal. Such "hybrid" exposure control systems are disclosed in U.S.Pat. No. 3,464,332, entitled "Automatic Exposure Control System", by R.H. Davison et al., issued Sept. 2, 1979 in common assignment herewith,U.S. Pat. No. 3,975,744, entitled "Automatic Exposure Control System",by B. K. Johnson et al., issued Aug. 17, 1976, and U.S. Pat. No.4,047,190, entitled "Hybrid Exposure Control System Employing DualMaximum Blade Displacement", by B. K. Johnson et al., issued Sept. 6,1977. Such "hybrid" exposure control systems as those disclosed abovecontemplate only the use of an ordinary flash lamp as the source ofartificial illumination since the burn time of an ordinary flash lamp issufficiently long as to allow the exposure to be terminated by theclosing shutter blades. Thus such systems have not heretofore beenadapted for use with electronic flash.

Therefore, it is a primary object of this invention to provide a"hybrid" exposure control system for a photographic camera apparatusutilizing an electronic flash or strobe of the quench type for itssource of artificial illumination.

It is a further object of this invention to provide a "hybrid exposure"control system in which a quench strobe is fired at an appropriateaperture size corresponding to the determined camera-to-subject distanceand wherein the strobe is subsequently quenched as a function ofreflected scene light detected in correspondence with the reflectedscene light admitted to the film plane during the exposure interval.

Other objects of the invention will be in part obvious and will in partappear hereinafter. The invention accordingly comprises a mechanism andsystem possessing the construction, combination of elements andarrangement of parts which are exemplified in the following detaileddisclosure.

DESCRIPTION OF THE DRAWINGS

The novel features that are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with other objects and advantages thereof will bebest understood from the following description of the illustratedembodiment when read in connection with the accompanying drawingswherein:

FIG. 1 is a schematic circuit block diagram of the photographic exposurecontrol system and apparatus of this invention;

FIG. 2 is a front elevational view showing portions of the shutter blademechanism of FIG. 1;

FIG. 2a is a fragmentary front elevational view showing portions of theshutter blade mechanism of FIG. 2 at a different position;

FIG. 3 is a front elevational view showing the shutter blade mechanismof FIG. 2 in still another position;

FIG. 4 is a fragmentary front elevational view showing portions of theshutter blade mechanism of FIG. 2 in still another position;

FIG. 5 is a cross-sectional view across the lines 5--5 of FIG. 2;

FIG. 6 is a flowchart showing an automatic sequence of operations forthe exposure control system of FIG. 1.

SUMMARY OF THE INVENTION

A photographic camera for use with an electronic flash of the quenchtype and including means for defining a film plane comprises arangefinding means for providing an output response generallycorresponding to the distance from the camera to a photographic subjectto be photographed. There is also included a blade mechanism togetherwith means for mounting the blade mechanism for displacement from aninitial closed arrangement wherein the blade mechanism precludes scenelight from being transmitted to the film plane to an open arrangementwherein the blade mechanism defines a maximum size aperture to allow thepassage of scene light to the film plane and then to a final closedarrangement wherein the blade mechanism again precludes scene light frombeing transmitted to the film plane. Actuatable drive means are alsoprovided for effecting the displacement of the blade mechanism from itsinitial closed arrangement to its open arrangement and then to its finalclosed arrangement to define an exposure interval in which scene lightis incident upon the film plane. Means are provided for detecting andintegrating scene light in correspondence with the scene light admittedby the blade mechanism to the film plane during the photographicexposure interval and for providing an output signal in response to thedetected and integrated scene light. Control means respond to the outputresponse from the rangefinding means to provide a flash fire signalduring the exposure interval to ignite the electronic flash when theblade mechanism defines an aperture value corresponding to thecamera-to-subject distance. The control means thereafter respond to theoutput signal from the scene light detecting and integrating means toprovide a quench signal to quench the electronic flash. In this manner,the exposure is determined as a "hybrid" function of bothcamera-to-subject range and scene brightness.

The control means further operate to maintain a select ratio betweenthat portion of the film exposure attributable to ambient scene lightand reflected flash light within determinate limits of camera-to-subjectdistance and ambient scene light intensity. The scene light detectingand integrating means may also comprise first and second photoresponsiveelements for receiving scene light in correspondence with the scenelight admitted by the blade mechanism to the film plane to provide afirst output signal responsive to the scene light incident to the firstphotocell and a second photocell output responsive to the scene lightincident to the second photocell. The control means also respond to thefirst output signal from the scene light detecting and integrating meansto provide a blade close command signal and thereby actuate the drivemeans to effect the displacement of the blade mechanism back to itsfinal closed arrangement. The control means also respond to the secondoutput signal from the scene light detecting and integrating means toprovide the quench signal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 1 there is shown at 10 a schematic circuit blockdiagram for the photographic camera apparatus of this invention. Thecamera apparatus 10 includes an objective lens arrangement or assemblyas shown in simplified fashion at 12, disposed for movement between aplurality of different focal positions. During each film exposureoperation, the objective lens assembly 12 is displaced to one of itsfocal positions for focusing at a focal plane 14, image-forming lightrays from a respective photographic subject as shown at 16 locatedwithin a given range of distances from the camera apparatus. As isreadily apparent, the lens assembly 12 has adapted each of its pluralityof focal positions to focus at the focal plane 14 of the camera, animage of a photographic subject located at a different distance from thecamera within the given range of distances.

Lens assembly 12 is biased to move through its plurality of differentfocal positions by a tension spring 18 and may be held at an initialterminal position as shown at solid lines by a releasable latch 20. Aspring 18 operates to bias the lens assembly 12 to move toward anotherterminal position as shown by the phantom lines. The lens assembly 12while in its initial terminal position (solid lines) operates to focusimage-forming light rays from a photographic subject located at theclosest possible distance to the camera within the aforementionedcamera-to-subject distance range and while in its other terminalposition (phantom lines) operates to focus image-forming light rays froma photographic subject located at the furthest possible distance fromthe camera within the aforementioned camera-to-subject distance range.The movement of the lens assembly 12 from its initial terminal positiontowards its other terminal position operates to progressively focusimage-forming rays from corresponding subjects located at progressivelyincreasing distances from the camera.

The photographic camera apparatus 10 is also provided with a sonicrangefinder as shown generally at 22 and which is more fully disclosedin U.S. Pat. No. 4,167,316, entitled "Sonar Controlled Lens FocusApparatus", by B. K. Johnson et al., issued Sept. 11, 1979, in commonassignment herewith and now incorporated by reference herein. The sonicrangefinder 22 includes a ranging circuit 24 which may be actuated in amanner to be herein described to issue a transmit commence signal to asonic transducer 26 so as to cause the transmission of a sonar rangingsignal comprising a burst of sonic energy as shown at 28. The transducer26 thereafter operates to detect an echo signal reflected from thephotographic subject 16 at an elapsed time interval subsequent to thetransmission of the sonar ranging signal. An echo detector 30 thenprovides a signal indicative of this elapsed time period whichcorresponds directly to the distance between the camera and the subject16 to be photographed. Thus, the sonic rangefinder 22 provides anindication of an elapsed time period which corresponds directly to thedistance between the camera and the subject to be photographed forreasons which will become more apparent in the following paragraphs.

Intermediate the objective lens arrangement 12 and the focal plane 14,there is provided a shutter mechanism that is shown generally at 32comprising two overlapping shutter blade elements 34 and 36 (see FIGS.2-5) of the so-called scanning type which will be subsequently describedin greater detail herein. The photographic camera apparatus is alsoprovided with a photographic cycle initiating button as shown at 38 inFIG. 1 wherein the depression of the button 38 operates to commence anexposure interval by ultimately effecting the release of the shutterblade elements 34 and 36 in a manner to be subsequently describedherein.

Referring now to FIGS. 2-5, it can be seen that a pair of scene lightadmitting primary apertures 40 and 42 are provided, respectively, in theblade elements 34 and 36 to collectively define a progressive variationof effective primary aperture openings in accordance with simultaneouslongitudinal and lateral displacement of one blade element with respectto the other blade element in a manner as is fully described in U.S.Pat. No. 3,942,183, entitled "Camera with Pivoting Blades", by G. D.Whiteside, issued Mar. 2, 1976, in common assignment herewith and nowincorporated by reference herein. The apertures 40 and 42 areselectively shaped so as to overlap a light entry exposure opening 44 ina baseblock casting 46 thereby defining a gradually varying effectiveaperture size as a function of the position of the blade elements 34 and36. The shutter blade element 34 has two spaced apart photocell sweepsecondary apertures 48 and 52 which overlap, respectively, two spacedapart photocell sweep secondary apertures 50 and 54 in the shutter bladeelement 36. The secondary photocell sweep apertures 48, 50, 52 and 54are configured in correspondence with the shapes of the scene lightadmitting primary apertures 40 and 42 and, as is readily apparent, movein correspondence with the primary apertures 40 and 42 to define twospaced apart pairs of small secondary apertures for admitting thepassage of scene light to a scene light detecting station as showngenerally at 56.

The scene light detecting station 56, in turn, comprises twophotoresponsive elements 58 and 60 which may be discrete photodiodesformed on a single integrated circuit chip. As is readily apparent, thephotoresponsive element 58 is aligned to receive scene light by way ofthe effective secondary aperture defined by the overlapping photocellsweep apertures 48 and 50, while in like manner the photoresponsiveelement 60 is aligned to receive scene light by way of the effectivesecondary aperture defined by the overlapping photocell sweep apertures52 and 54.

Light from the scene is directed to the photocell sweep secondaryapertures by a photocell lens 62 having an upper lens portion 64preferably overlayed with a spectral filter 68 and a lower lens portion66 having no spectral filter overlay. In the preferred mode, thespectral filter 68 will be of a type that will attenuate electromagneticfrequencies in the near IR region (e.g., 700-1200 nanometers). Thus, theupper lens portion 64 including the spectral filter 68 will transmitvisible spectral energy to the exclusion of infrared spectral energywhereas the lower lens portion 66 will transmit both IR frequencyspectral energy as well as visible spectral energy. It will also be wellwithin the scope of this invention to provide the lower lens portion 66with an overlay spectral filter which would operate to pass onlyinfrared spectral energy while attenuating visible spectral energy.

Projecting from the baseblock casting 46 at a location spaced laterallyapart from the light entry exposure opening 44 is a pivot pin or stud 70which pivotally and translatably engages elongate slots 72 and 74 formedin respective shutter blade elements 34 and 36. Pin 70 may be integrallyformed with the baseblock casting 46, and blade elements 34 and 36 maybe retained in engaging relation with respect to the pin 70 by anysuitable means such as peening over the outside end of the pin 70.

The opposite ends of the blade elements 34 and 36 respectively includeextended portions which pivotally connect to a walking beam 76. Thewalking beam 76, in turn, is disposed for rotation relative to thebaseblock casting 46 by pivotal connection to a projecting pivot pin orstud 78 which may be integrally formed with the baseblock casting 46 ata location spaced laterally apart from the light entry exposure opening44. The walking beam 76 may be pivotally retained with respect to thepin 78 by conventional means such as an E ring (not shown). In thepreferred mode, the walking beam 76 is pivotally connected at its distalends to the shutter blade elements 34 and 36 by respective pin members80 and 82 which extend laterally outward from the walking beam 76. Pinmembers 80 and 82 are preferably circular in cross section and extendthrough respective openings in respective blade elements 34 and 36 so asto slidably engage respective arcuate tracks 84 and 86 which may beintegrally formed within the baseblock casting 46. The arcuate tracks 84and 86 operate to inhibit disengagement of the blade elements 34 and 36from their respective pin members 80 and 82 during operation of theexposure control system. Thus, the walking beam 76 and shutter bladeelements 34 and 36 collectively define a blade mechanism together with ameans for mounting the blade mechanism for displacement including pivotpins 70 and 78.

Drive means are provided for displacing the blade mechanism 32 andinclude a tractive electromagnetic device in the form of a solenoid 88employed to displace the shutter blades 34 and 36 with respect to eachother and the baseblock casting 46. The solenoid 88 includes aninternally disposed cylindrical plunger unit 90 which retracts inwardyinto the body of the solenoid upon energization of the solenoid winding.The plunger 90 includes an endcap 92 at the outside end thereof togetherwith a vertical slot or groove 94 within the endcap 92 for looselyengaging a pin 96 extending outwardly from the walking beam 76. In thismanner, the solenoid plunger 90 is affixed to the walking beam 76 sothat longitudinal displacement of the plunger 90 will operate to rotatethe walking beam around the pivot pin 78 so as to appropriately displacethe shutter blades 34 and 36. The drive means may additionally include ahelical compression spring 98 so as to continuously urge the bladeelements 34 and 36 into positions defining their largest effectiveaperture over the light entry exposure opening 44. As will be readilyunderstood in some shutter blade arrangements, it may be preferable touse a tension spring in place of the compression spring 98 in a manneras is shown in U.S. Pat. No. 4,040,072, entitled "Shutter LatchArrangement Releasable Through Shutter Blade Actuation and ResettableThrough Film Advancement", by B. K. Johnson, issued Aug. 2, 1977, incommon assignment herewith and now incorporated by reference herein.Thus, with the spring connection herein described, the exposure controlsystem of this invention is biased to continuously urge the shutterblade elements 34 and 36 into an open orientation.

The shutter blade elements 34 and 36 are respectively provided withanother set of scene brightness detect apertures 100 and 102. The scenebrightness detect apertures 100 and 102 overlap each other to provide anaperture of predetermined value that is aligned with the photoresponsiveelement 58 so as to permit passage of light from the scene to impingeupon the photoresponsive element 58 when the shutter blades 34 and 36are moved to the positions as shown in FIG. 2 in a manner to be morefully described in the following paragraphs.

In order that the shutter blade elements 34 and 36 may be maintained intheir scene light blocking arrangement without requiring a continuousenergization of the solenoid 88, there is provided a latch mechanism 104of a type as is fully described in U.S. Pat. No. 4,040,072, supra.

The camera is preferably intended for use with an electronic flash orstrobe of the quench type as shown at 106 wherein the strobe triggeringand quenching circuits may all be of types well known in the art. Thequench strobe 106 preferably derives charging power from a battery thatis insertable within the camera in correspondence with the film pack orcassette in a manner that is well known in the art for Polaroid SX-70type film cassettes and cameras.

The aforementioned film cassette battery is also preferably utilized topower the circuitry of FIG. 1 in its entirety by way of three switchesS₁, S₂ and S₃ in a manner as is more fully described in U.S. Pat. No.4,040,072, supra. The camera of this invention is also provided with anexposure and sequencing circuit 108 and a motor and solenoid controlcircuit 110 which operate in a manner also more fully described in U.S.Pat. No. 4,040,072, supra. As is readily apparent, the motor andsolenoid control circuit 110 operates to control the energizing currentdelivered to the solenoid 88 and to a motor 112. The film units intendedfor use with a camera of this invention are preferably of theself-developing type, and the motor 112 is provided to effect theadvancement and processing of the self-developing film units in awell-known manner.

Referring now to FIG. 6 in conjunction with FIG. 1, there is shown asequence of operations through which the camera is automatically guidedto provide artificial illumination by way of the quench strobe 106 undervarying conditions of ambient scene light intensity andcamera-to-subject range. In order for a photographer to commence aphotographic exposure cycle, he must first energize the quench strobe106 by manually actuating a strobe charge button 114 (block A) so as toclose switch S₄ and effect the charging of the strobe 106 in awell-known manner. During the time that the strobe 106 is charging(block B) there is provided an affirmative logic signal which isoperative to energize an LED 116 in a manner as is fully described inU.S. Pat. No. 4,192,587, entitled "Proportional Fill Flash", issued Mar.11, 1980, in common assignment herewith and now incorporated byreference herein. The light from the LED 116 is made visible to thephotographer and thus provides him with a visual indication that thestrobe 106 is in a state of charging and that the photographic cycleinitiating button 38 should not be depressed. However, if thephotographer should try to actuate the photographic cycle initiatingbutton 38 prematurely prior to the strobe 106 reaching its fully chargedcondition while the LED 116 is energized, there may be provided a systemfor inhibiting the camera in a manner as is more fully described in U.S.Pat. No. 4,064,519, entitled "Regulated Strobe for Camera With SixthFlash Inhibit", by R. C. Kee, issued Dec. 20, 1977, in common assignmentherewith and now incorporated by reference herein.

When the strobe 106 is fully charged in readiness for a photographicexposure cycle, there is provided the requisite affirmative logic signalto turn off the LED 116 (block C) in a manner as is more fully describedin U.S. Pat. No. 4,192,587, supra. Once the LED 116 is deenergized, aphotographer may initiate a photographic exposure cycle by manuallyactuating the button 38 so as to close the switch S₁ (block C) in themanner as is fully described in U.S. Pat. No. 4,040,072, supra. Closureof the switch S₁, in turn, energizes the exposure sequencing circuit 108so as to provide a solenoid drive signal to the motor and solenoidcontrol circuit 110. The motor and solenoid control circuit 110, inturn, energizes the solenoid 88 (block D) to retract the plunger 90inwardly and rotate the walking beam 76 in a counterclockwise directionfrom an intermediate position in which the photocell sweep secondaryapertures and scene brightness apertures are aligned in position asshown in FIG. 2a to a terminal position as shown in FIG. 2. This limitedcounterclockwise rotation of the walking beam 76 operates in a manner asis again more fully described in U.S. Pat. No. 4,040,072, supra, toaffect the release of the shutter latch 104 while at the same timeaffecting the closure of the switches S₂ and S₃ (block D).

Closure of the switch S₃ also operates to signal a solenoid hold logiccircuit 117 to provide an affirmative logic signal to the motor andsolenoid circuit 110 so as to power down the solenoid 88 from the highinitial current energization condition required to retract the plunger90, to a low current energization condition (block E) required to holdthe plunger in its retracted position as shown in FIG. 2 and as is fullydescribed in U.S. Pat. No. 4,192,587, supra.

Closure of the switch S₃ also operates to actuate the sonar rangefinder22 to transmit a sonar ranging signal 28 (block E) in the followingmanner. Closure of the switch S₃ provides an affirmative logic signal toan inhibit circuit 118 so as to remove the inhibit imposed on the sonarrangefinder circuit 22 and thereby actuate the sonar rangefindingcircuit 22 to issue a transmit commence signal to the sonic transducer26. The latch 20 is withdrawn in response to the transmit command issuedby the ranging circuit 24 thereby releasing the lens assembly 12 to movefrom its close-up focus position (solid lines) towards its far distancefocus position (phantom lines). A lens halting mechanism as showngenerally at 15 operates in response to the output of the echo detector30 which detects the echo signal reflected from the photographic subject16 at an elapsed time interval subsequent to the transmission of thesonar ranging signal (block F). The lens halt mechanism 15 therebyoperates to interrupt the movement of the lens assembly 12 subsequent toits initial displacement from its close-up focus position at an elapsedtime interval which correlates to the elapsed time interval betweentransmission of the sonar ranging signal and receipt of the echo fromthe photographic subject. The photographic subject will thus preferablybe focused in the elapsed time interval (real time) between thetransmission of the sonar ranging signal and the receipt of the echo bythe sonic rangefinder 22. As will be readily understood, the dynamiccharacteristics of the lens assembly 12 drive, which in theaforementioned example constitutes the spring 18, operates to move thelens assembly through its plurality of focal positions at a rate suchthat the lens assembly 12 reaches each one of its plurality of focalpositions at substantially the same time at which an echo from the sonarranging signal could be received by the echo detector 30 subsequent tobeing reflected from a subject located at the camera-to-subject distancedirectly corresponding to that one focal position.

Closure of the switches S₂ and S₃ which operate to power down thesolenoid 88 to its holding current mode and to commence the transmissionof the sonar ranging signal in the aforementioned manner also providesan affirmative logic signal to enable an up/down counter as showngenerally at 120 (block E). The up/down counter 120 is thus disabledprior to the closure of the switch S₃ while the solenoid 88 is in itscurrent driving mode and is thereafter enabled to provide a count by anaffirmative logic signal provided upon closure of the switch S₃ in amanner as is more fully described in U.S. Pat. No. 4,192,587, supra. Acount is provided to the up/down counter 120 by an oscillator 126 whichprovides a 30 kilohertz output clock pulse train. The 30 kilohertzoutput clock pulse train from the oscillator 126, in turn, is directedsimultaneously to a first divide circuit 128 wherein the 30 kilohertzclock pulse train is divided to provide an output clock pulse train of18 kilohertz and another divide circuit 130 wherein the 30 kilohertzclock pulse is divided to provide a 10 kilohertz output clock pulsetrain for reasons which will become apparent from the followingdiscussion. The output clock pulse trains from the divide circuits 128and 130, in turn, are directed to a gate 132 which directs one of theinputted clock pulse trains to the up/down counter 120 in a manner to besubsequently described.

The output from the rangefinding circuit 22 is directed to a receiveecho latch circuit 138 which prior to the receipt of the echo signalprovides an affirmative logic signal to the up/down terminal of thecounter 120 so as to set the mode of the counter 120 to count "up" priorto receipt of the ranging signal. The affirmative logic signal providedby the receive echo latch 138 prior to receipt of the ranging signal isalso directed to the gate 132 so as to set the gate 132 to transmit the10 kilohertz clock pulse train from the divide circuit 130 to input theup/down counter 120. In this manner the up/down counter 120 is actuatedto count up the 10 kilohertz clock pulse at the instant that the sonarranging signal is transmitted by the sonar rangefinding circuit 22(block E).

As is readily apparent, movement of the shutter blade mechanism 32 toits terminal position as shown in FIG. 2 also operates to move the scenebrightness detect apertures 100 and 102 from their positions as shown inFIG. 2a into overlapping relationship with respect to each other asshown in FIG. 2 so as to admit scene light through the top half lensportion 64 of the photocell lens 62 to the photoresponsive element 58.The photoresponsive element 58, in turn, responds to the incidentambient scene light to provide an output signal to a light integratingcircuit 136 as shown in FIG. 1. The light integrating circuit 136integrates the output signal in a manner to be subsequently described ingreater detail herein from the photoresponsive element 58 to provide anoutput signal to a brightness measurement circuit as shown generally at134 (block E). The brightness measurement circuit 134, in turn, providesa first selected logic output signal level if the detected scene lightintensity is below a determinate level and a second selected logicsignal level if the intensity of detected scene light is above thedeterminate level. The determinate level above which the brightnessmeasurement provides the second logic signal level and below which itprovides the first logic signal level is preferably established to be 10c/ft². The logic signals from the brightness measurement circuit 134, inturn, are simultaneously directed to the gate 132 to control the gate132 in a manner to be subsequently described and to a quench level gate140 for reasons also to be subsequently described.

Receipt of the echo signal by the transducer 26 signals the echodetector 30 to provide an output signal to trigger the receive echolatch 138 so as to remove the affirmative output logic signal therefromto the gate 132 and thereby stop the 10 kilohertz clock pulse from beingcounted by the up/down counter 120 while at the same time changing thecounter 120 from an "up" mode of counting to a "down" mode of counting(block F) in a manner as is fully described in U.S. Pat. No. 4,192,587,supra. The change in the affirmative logic signal level from the receiveecho latch 138 upon the receipt of the echo signal by the sonarrangefinder 22 is also directed to the motor and solenoid controlcircuit 110 so as to affect the deenergization of the solenoid 88 andthereby commence the exposure cycle (block F). The change in the outputof the affirmative logic signal from the receive echo latch 138 upon thereceipt of the echo signal by the rangefinder 22 is also directed to adelay circuit 142. The output from the delay circuit 142, in turn, isdirected to energize the LED 116 (block G) for reasons which will becomemore apparent from the following discussion.

In the event that the photographic subject should be located at aninfinite distance from the camera, which by way of this example may beconsidered to be any distance greater than 30 feet, then the counter 120will fill and provide an affirmative logic signal level at outputterminal α (block F). The affirmative logic signal provided from theoutput terminal α of the up/down counter 120 upon an infinite count isidentical to the change in the output signal level provided from thereceive echo latch 138 upon receipt of the echo signal by the sonarrangefinder 22 and thereby operates in the aforementioned manner toterminate the "up" count by the counter 120 while simultaneouslydeenergizing the solenoid 88 to release the shutter blade elements 34and 36 to commence an exposure cycle (block F). As previously discussed,the LED 116 is thereafter energized to provide light 10 millisecondsafter the shutter blade elements are released.

The deenergization of the solenoid 88 results in a clockwise rotation ofthe walking beam 76 under the biasing force of compression spring 98from its scene light blocking position as shown in FIG. 2 toward itsmaximum scene light admitting position as shown in FIG. 3. As is readilyapparent, the walking beam 76 must be rotated through a limited degreebefore the primary scene light admitting apertures 40 and 42 overlap toadmit scene light to the focal plane 14. Whereas the photocell sweepsecondary apertures 48, 50, 52 and 54 move in correspondence with theprimary apertures 40 and 42, the walking beam 76 must be rotated througha limited number of degrees before the first scene light is alsoadmitted by the photocell sweep secondary apertures to thephotoresponsive elements 58 and 60.

The LED 116 is preferably aligned coaxially with respect to thephotoresponsive element 58 on the opposite side of the shutter bladeelements 34 and 36 so as to provide illumination detectable by thephotoresponsive element 58 when the secondary apertures 48 and 50 firstoverlap without interfering with the transmission of scene light throughthe apertures 48 and 50. Alternatively, separate apertures may beprovided to admit the light from the LED 116 to the photoresponsiveelement 58 in synchronism with the commencement of the exposure intervalas further described in U.S. Pat. No. 3,628,437, entitled "PhotographicCamera", issued Dec. 21, 1971, and now incorporated by reference herein.As previously described, the LED 116 is energized to provideillumination 10 milliseconds subsequent to the release of the shutterblade elements 34 and 36 (block G). The 10 millisecond delay inenergizing the LED 116 assures that light from the LED will not beadmitted to the photoresponsive element 58 by the scene brightnessdetect apertures 100 and 102. Thus regardless of the actual ambientscene light conditions, an indication may be provided as to the firstinstance at which the primary apertures 40 and 42 overlap to admit scenelight to the focal plane 14 by way of the light from the LED 116 beingadmitted to the photoresponsive element 58 at the instant that thesecondary apertures 48 and 50 first overlap.

The photoresponsive element 58 responds to the light emitted from theLED 116 at the instant that the secondary apertures 48 and 50 firstoverlap to provide an output signal to the integrator 136. Theintegrator circuit 136 comprises a current-to-frequency converter 144the output of which is directed to a gate 146 which, in turn, providesan output to a counter 148. The current-to-frequency converter 144 maybe of a type as is fully described in U.S. Pat. No. 4,306,786, entitled"Photographic Exposure Control With Scene Light Integration LevelDetermined as Function of Preexposure Ambient Scene Light Detect", by P.P. Carcia et al., issued Dec. 22, 1981, in common assignment herewithand now incorporated by reference herein. The integration circuit 136 isturned on in coincidence with the LED 116 by receipt of an affirmativelogic signal from the delay circuit 142 to enable the counter 148 tostart counting. The output from the integrator 136, in turn, is directedto three counter decode circuits 158, 160 and 162. The decode circuit158 is signaled to provide an affirmative logic signal to enable thegate 132 upon the detection of the first light provided by the LED 116.The decode circuit 158 may be signaled to provide its affirmative logicoutput signal upon the counter 148 counting pulses equivalent to 0.1 ofan optimum exposure value. The affirmative logic output signal from thedecode circuit 158 is also directed to the LED 116 so as to turn off theLED (block G).

The gate 132 is thus enabled to transmit one of the clock pulse trainsfrom either the divide circuit 128 or the divide circuit 130 to theup/down counter 120 upon receipt of an affirmative logic signal from thedecode circuit 158 at the commencement of the exposure interval. As waspreviously discussed, the counter 120 is already in a "down" mode andwill count down the respective clock pulse train provided thereto by thegate 132. Under low ambient scene light conditions where the scene lightintensity is less than 10 c/ft², the gate 132 will be enabled by thebrightness measurement circuit 134 to gate the 10 kilohertz clock pulsetrain to the counter 120 and the counter 120 will count down at the samerate at which it previously counted up (block O). Conversely, under highambient scene light intensity conditions (above 10 c/ft²), the gate 132will be enabled by the brightness measurement circuit 134 to gate the 18kilohertz clock pulse train to the counter 120 and will count down at arate of 1.8 times faster than the rate it previously counted up (blockH).

The decode circuit 160 is connected to decode the counter 148 upondetection of sufficient scene light to provide at least 0.7 of theoptimum exposure value. In like manner, the decode circuit 162 isconnected to decode the counter 148 upon detection of scene lightsufficient to provide an optimum exposure value. Thus, under conditionsof low ambient scene light intensity of less than 10 c/ft², the counter120 will count down to empty prior to the output from the lightintegrator 136 reaching a sufficient count to signal the decode 160.When the counter 120 empties, a counter status circuit 122 will switchto provide an affirmative logic output signal which will be gated by anOR gate 124 to both disable the counter 120 and to provide a flash firesignal to the strobe 106. Thus, the strobe 106 and its associated flashtube is fired in a well-known manner (block P). The counter 120 bycounting down the 10 kilohertz input clock pulse provides a rangeresponsive time signal commencing in correspondence with the initiationof the exposure interval and terminating at a subsequent timecorresponding to the distance between the camera and the subject to bephotographed. In this manner, the strobe is fired at a "hybrid" apertureslightly larger than the so-called "follow-focus" aperture. As will bereadily understood, the "follow-focus" aperture is the appropriateexposure aperture size which would be computed based on the determinedcamera-to-subject distance, i.e., focus distance, utilizing the inversesquare law of light energy propagation which may additionally beweighted to anticipate spurious room reflections in a well-known manner.

The flash fire signal to the strobe 106 from the counter status circuit122 is also directed to the gate circuit 146 so as to switch the gatefrom its previous mode in which the output from the current-to-frequencyconverter 144 was directed to the counter 148 to another mode in whichthe output from a sample frequency circuit 164 is directed PG,25 to thecounter 148 for the anticipated duration of the electronic flash pulse.The frequency of the output clock pulse train from the sample frequencycircuit 164 may be derived in a well-known manner from the frequency ofthe clock pulse train provided by the current-to-frequency converter 144immediately prior to the firing of the strobe 106.

The flash fire signal to the strobe 106 is also simultaneously directedto a light integrator circuit 166 which may be of a well-known analogtype which integrates the output signal from the photo-responsiveelement 60. The output signal from the light integrator 166 is directedto two level detect circuits 168 and 170 which trigger respectively inresponse to the detection and integration of light sufficient to provide0.3 of the optimum exposure value and 1.0 of the optimum exposure value.The outputs from the quench level detectors 168 and 170, in turn, aredirected to the quench level gate 140 which is controlled as a functionof the previous brightness measurement from the brightness measurementcircuit 134. Thus, under the aforementioned conditions of low ambientscene light intensity of less than 10 c/ft², the brightness measurementcircuit 134 provides an affirmative output logic signal to the quenchlevel gate 140 so as to enable the gate 140 to transmit the outputresponse from the quench level detect circuit 170. Thus, thephoto-responsive element 60 and the light integrator 166 will detect andintegrate, respectively, the flash light reflected from the photographicsubject 16 until triggering the quench level detect circuit 170 so as toprovide an affirmative logic signal which will be transmitted by way ofthe quench level gate 140 to provide a quench signal to the quenchstrobe 106 (block Q).

As is now readily apparent, the flash quench signal is provided as afunction of the detection of reflected flash light through an effectivesecondary aperture, i.e., defined by the overlapping photocell sweepapertures 52 and 54, which corresponds to the effective primary aperturedefined by the overlapping apertures 40 and 42. In addition, since theincident scene light to the photo-responsive element 60 is directedthrough the bottom half lens portion 66, there is provided a differentspectral response to the light energy controlling the strobe quench thanthe spectral response of the light energy transmitted by the top halflens portion 64 to the photo-responsive element 58 which ultimatelydetermines the instant of shutter blade closing under conditions of highambient scene light intensity above 10 c/ft² in a manner to besubsequently described. In this manner the quench strobe may becontrolled as a function of the detection and integration of scene lightspectrally weighted to include the infrared frequencies which aregenerally more uniformly reflected from the scene and thus provide lesschance for the subject matter of the scene being overexposedparticularly against a dark background.

Whereas the gate 146 operates during the duration of the flash firing toblock the transmission of the clock pulse train from thecurrent-to-frequency converter 44 and instead transmits the output clockpulse train from the sample frequency circuit 164 to the counter 148,there in effect is no integration of the reflected strobe light and thecounter 148 will likely not count a sufficient number of clock pulses tosignal the decode 160. However, the affirmative logic output signal fromthe counter status circuit 122 is also directed to a time delay circuit154 which, in turn, switches after a predetermined time delay to providean affirmative logic signal by way of an OR gate 156 to the motor andsolenoid control circuit 110 so as to effect the energization of thesolenoid 88 and drive the shutter blade elements 34 and 36 back to theirscene light blocking arrangement as shown in FIG. 2. The time delaycircuit 154 may be arranged to provide a shutter blade closing commandsignal 29 milliseconds subsequent to the initiation of the flash firesignal when the photographic subject is located at distances less thaninfinity from the camera and at one second subsequent to the terminationof the flash fire pulse when the photographic subject is located atdistances equal to infinity (greater than 30 feet) from the camera in amanner as is well-shown in U.S. Pat. No. 4,192,587, supra.

Under conditions of high ambient scene light intensity greater than 10c/ft², it can be seen that the brightness measurement circuit 134operates to provide an affirmative logic signal to the gate 132 so as toenable the transmission of the 18 kilohertz clock pulse train from thedivide circuit 128 to the up/down counter 120. In addition, theaffirmative logic signal from the brightness measurement circuit 134 isalso directed to the quench level gate 140 so as to transmit the outputsignal upon the triggering of the quench level detect 168. Thus, thefirst light that is admitted to the photoresponsive element 58 from theLED 116 operates to signal the decode 158 in the aforementioned mannerso as to enable the gate 132 to transmit the 15 kilohertz clock pulsetrain from the divide by two circuit 128 to the counter 120 and therebyinitiate the aforementioned countdown in synchronization with theinitiation of the film exposure (block H). Thus, there is provided arange responsive time signal commencing in correspondence with theinitiation of the exposure interval and terminating at a subsequent timecorresponding to the distance between the camera and the subject to bephotographed.

In the event that the photographic subject is located close enough tothe camera so that the counter 120 counts down to empty prior to theoutput signal from the integrator 136 being decoded by the decode 160,there will occur a switching of the counter status circuit 122 toprovide an affirmative logic signal by way of an OR gate 124 to fire thequench strobe 106 in the aforementioned manner (block I). Again, theflash fire signal operates to control the gate 146 so that itdiscontinues the transmission of the output clock pulse train from thecurrent-to-frequency converter 144 and instead transmits the outputclock pulse train from the sample frequency circuit 164 to the counter148. Simultaneous to this, the light integrator 166 is also enabled tointegrate the light detected by the photoresponsive element 60 so as toprovide an output to trigger the quench level detect 168. As previouslydiscussed, the affirmative output signal from the triggered quench leveldetect 168 is transmitted by the quench level gate 140 to provide thequench signal to the strobe 106 (block J). Thus, the strobe is quenchedsubsequent to detecting an amount of reflected flash light sufficient toprovide 0.3 of the optimum exposure value. At the same time theintegrator 136 is disabled from integrating the scene light detected bythe photoresponsive element 58 and instead provides an output which maybe based upon the ambient scene light detected immediately prior to thefiring of the strobe 106.

After the strobe 106 is quenched, the gate 146 is switched to againblock the transmission of the output clock pulse train from the samplefrequency circuit 164 and to again transmit the output clock pulse trainfrom the current-to-frequency converter 144. Thus, the detection andintegration of ambient scene light is resumed subsequent to firing thestrobe until the counter 148 is decoded by the decode circuit 160 uponreaching a count indicative of the detection of an amount of scene lightsufficient to provide 0.7 m of the optimum exposure value. The decodecircuit 160 thereafter provides an affirmative logic signal to one inputterminal of an AND gate 172 which was previously enabled by theaffirmative output logic signal from the counter status circuit 122 tothe other output terminal thereof by way of an OR gate 174. Theaffirmative logic output signal from the AND gate 172 is thereaftertransmitted by the OR gate 156 to the motor and solenoid control circuit110 so as to effect deenergization of the solenoid 88 and thereby rotatethe shutter blade elements 34 and 36 back to their scene light blockingposition as shown in FIG. 2 (block K).

In this manner means are provided for discounting the artificialillumination provided by the quench strobe 106 so that a selectproportion of the optimum film exposure value is directly provided byambient scene light, while the remaining proportion of the optimum filmexposure value is directly attributable to the artificial scene lightprovided by the quench strobe 106. In the illustrated embodiment 30percent of the optimum film exposure value may be directly attributableto the artificial scene light provided by the quench strobe 106, while70 percent of the film exposure value may be directly attributable tothe ambient scene light. These proportions are established, for example,by the 0.7 level at which the decode 160 is signaled and the 0.3 optimumfilm exposure level at which the quench detect 168 is triggered.

Also, it should be readily appreciated that by counting down at thefaster clock rate of 18 kilohertz, there is provided a decrease in theduration of the range responsive time signal by a constant factor (1.8)in response to the high ambient scene light intensity above 10 c/ft².The decrease in the duration of the range responsive time signal affectsthe firing of the strobe 106 at a shorter time subsequent to thecommencement of the exposure interval than the time at which the strobe106 would otherwise be fired under conditions of low ambient scene lightintensity of less than 10 c/ft². Whereas the opening speed of theshutter blade elements 34 and 36 is generally constant, it is readilyapparent that the strobe 106 is fired sooner and at a smaller apertureduring the high ambient scene light intensity mode of operation thanduring the aforementioned low ambient scene light intensity mode ofoperation. Preferably, the strobe 106 is fired at a determinate numberof stops smaller aperture during the high ambient scene light intensitymode of operation than it would be during the low ambient scene lightintensity mode of operation for a subject located at the same distancefrom the camera.

Photographic subjects may be located at too great a distance from thecamera to maintain the aforementioned proportion between ambient andartificial scene light in which case there is provided a so-calledtransient mode of operation where the decode circuit 160 will besignaled to provide an affirmative output logic signal prior to thecounter 120 emptying and signaling the counter status circuit 122 toprovide its affirmative logic output signal. In this situation, theaffirmative output logic signal from the decode circuit 160 will bedirected by way of the OR gate 124 to provide the flash fire signal tothe quench strobe 106 (block L). The strobe will fire in theaforementioned manner and the scene light detection and integration toquench the strobe will be by way of the photoresponsive element 60 andintegrator 166, respectively, as previously described (block M).Subsequent to the quench signal, the photoresponsive element 58 willagain provide the input signal to the integrator 136 which will continueto integrate until signaling the decode circuit 162 to provide anaffirmative output logic signal. Thus, the affirmative output logicsignal from the decode 162 will be directed by way of the OR gate 174and AND gate 172 previously enabled by the affirmative output logicsignal from the decode circuit 160 to provide by way of the OR gate 156,the shutter blade closing command signal to the motor and solenoidcontrol circuit 110 (block N).

In the event that the counter 120 should empty prior to the decodecircuit 162 being signaled, there will then be provided an affirmativeoutput logic signal by the counter status circuit 122 which, in turn,will be directed by way of the OR gate 174 to the AND gate 172previously enabled upon the decode circuit 160 being signaled. Theaffirmative output logic signal from the AND gate 172, in turn, will begated by the OR gate 156 to provide the shutter blade closing commandsignal to the motor and solenoid control circuit (block S).

Thus, there exists a race condition between the light integratorintegrating sufficient light to signal the decode circuit 162 to providethe shutter blade closing command enabling signal or the counter 120counting down to empty so as to provide the shutter blade closingcommand enabling signal. As should be readily apparent, during thistransient mode of operation the proportion of the film exposure valuedirectly attributable to the artificial scene light provided by thequench strobe 106 decreases from the aforementioned 30 percent in directcorrespondence with the increase in the subject-to-camera distance rangeuntil the artificial scene light provides no contribution to the filmexposure which is the situation where the decode circuit 162 is signaledto provide the shutter blade closing command enabling signal prior tothe counter 120 emptying.

In this manner there is provided a so-called "hybrid" exposure controlsystem which is responsive to both firing a flash at an appropriate"hybrid" aperture size calculated to generally correspond to thedetermined camera-to-subject distance in accordance with the inversesquare law of light and the detection and integration of reflectedstrobe light from the scene to provide a flash quenching signal. Thus,there is made possible an increased degree of correction with theso-called "hybrid" exposure control system, since a slight error in thedetermination of camera-to-subject range resulting in a slight error inthe aperture at which the strobe is fired can be easily compensated bythe detection and integration of the reflected strobe light to providethe flash quenching signal. In addition, by firing the strobe at the"hybrid" aperture, the amount of overexposure possible becomessubstantially reduced in comparison to a photographic system whichdepends solely upon the integration of reflected strobe light.

Other embodiments of the invention, including additions, subtractions,deletions and other modifications of the preferred disclosed embodimentsof the invention will be obvious to those skilled in the art and arewithin the scope of the following claims. For instance, the objectivelens arrangement 12 herein described may alternatively be a lens diskcomprising a plurality of circumferentially spaced apart lens elementswith the lens disk being actuated upon initial movement of the walkingbeam in a manner as is more fully described in U.S. Pat. No. 4,167,316,supra.

What is claimed is:
 1. A photographic camera for use with an electronicflash of the quench type and including means for defining a film plane,said camera comprising:rangefinding means for providing an outputresponse generally corresponding to the distance from the camera to aphotographic subject to be photographed; a blade mechanism; means formounting said blade mechanism for displacement from an initial closedarrangement wherein said blade mechanism precludes scene light frombeing transmitted to the film plane to an open arrangement wherein saidblade mechanism defines a maximum size aperture to allow the passage ofscene light to the film plane and then to a final closed arrangementwherein said blade mechanism again precludes scene light from beingtransmitted to the film plane; drive means responsive to the actuationthereof for effecting the displacement of said blade mechanism from itsinitial closed arrangement to its said open arrangement and then intoits final closed arrangement to define an exposure interval during whichscene light is incident upon the film plane; means for detecting andintegrating scene light in correspondence with the scene light admittedby said blades mechanism to the film plane during the photographicexposure interval and for providing an output signal in response to thedetected and integrated scene light; and control means responsive to theoutput response from said rangefinding means for providing a flash firesignal during the exposure interval to ignite the electronic flash whensaid blade mechanism defines an aperture value corresponding to saidcamera-to-subject distance and thereafter responding to said outputsignal from said scene light detecting and integrating means forproviding a quench signal for quenching the electronic flash, wherebysaid exposure is determined as a hybrid function of bothcamera-to-subject range and scene brightness, wherein said scene lightdetecting and integrating means comprises first and secondphotoresponsive elements for receiving scene light in correspondencewith the scene light admitted by said blade mechanism to the film planeto provide a first output signal responsive to the scene light incidentto said first photocell and a second output signal responsive to thescene light incident to said second photocell and wherein said controlmeans responds to said first output signal from said scene lightdetecting and integrating means for providing a blade close commandsignal to actuate said drive means to effect the displacement of saidblade mechanism back to its said final closed arrangement and to saidsecond output signal from said second light detecting and integratingmeans for providing said quench signal.
 2. The photographic camera ofclaim 1 wherein said control means maintains a select ratio between thatportion of the film exposure attributable to ambient scene light andreflected flash light within determinate limits of camera-to-subjectdistance and ambient scene light intensity.
 3. The photographic cameraof claim 1 wherein the detection and integration of scene light by wayof said second photoresponsive element is initiated in response to saidflash fire signal and wherein the detection and integration of scenelight by way of said first photoresponsive element is terminated inresponse to said flash fire signal for a determinate holding intervalgenerally corresponding to the time during which the flash is fired. 4.The photographic camera of claim 3 wherein said means for detecting andintegrating scene light also includes scene brightness detection meansfor providing prior to the exposure interval either a high scene lightsignal responsive to the detection of ambient scene light above a selectlevel or a low scene light signal responsive to the detection of ambientscene light below said select level and wherein said control meansoperates when said scene brightness means provides said low scene lightsignal to provide said quench signal upon the detection and integrationof substantially more scene light than is required to provide saidquench signal when said scene brightness means provides said high scenelight signal.
 5. The photographic camera of claim 3 including means forassuring that the spectral characteristic of the scene light incident tosaid first photoresponsive element is different from the spectralcharacteristic of the scene light incident to said secondphotoresponsive element.
 6. A photographic camera for use with anelectronic flash of the quench type and including means for defining afilm plane, said camera comprising:a blade mechanism; means for mountingsaid blade mechanism for displacement from an initial closed arrangementwherein said blade mechanism precludes scene light from beingtransmitted to the film plane to an open arrangement wherein said blademechanism defines a maximum size aperture to allow the passage of scenelight to the film plane and then to a final closed arrangement whereinsaid blade mechanism again precludes scene light from being transmittedto the film plane; drive means responsive to the actuation thereof foreffecting the displacement of said blade mechanism from its initialclosed arrangement to its said open arrangement and then into its finalclosed arrangement to define an exposure interval during which scenelight is incident upon the film plane; means for detecting andintegrating scene light comprising first and second photoresponsiveelements for receiving scene light in correspondence with the scenelight admitted by said blade mechanism to the film plane to provide afirst output signal responsive only to the scene light incident to saidfirst photocell and a second output signal responsive only to the scenelight incident to said second photocell; and control means for effectingan exposure interval and providing a flash fire signal during theexposure interval when said blade mechanism defines an appropriateaperture value, said control means responding to said first outputsignal from said scene light detecting and integrating means exclusiveof said second output signal to provide a blade close command signal toactuate said drive means to effect the displacement of said blademechanism back to its said final closed arrangement and to said secondoutput signal from said scene light detecting and integrating meansexclusive of said first output signal to provide a quench signal toquench the electronic flash.
 7. The photographic camera of claim 6wherein said control means maintains a select ratio between that portionof the film exposure attributable to ambient scene light and reflectedflash light within determinate limits of camera-to-subject distance andambient scene light intensity.
 8. The photographic camera of claim 7wherein the detection and integration of scene light by way of saidsecond photoresponsive element is initiated in response to said flashfire signal and wherein the detection and integration of scene light byway of said first photoresponsive element is terminated in response tosaid flash fire signal for a determinate holding interval generallycorresponding to the time during which the flash is fired.
 9. Thephotographic camera of claim 8 wherein said means for detecting andintegrating scene light also includes scene brightness detection meansfor providing prior to the exposure interval either a high scene lightsignal responsive to the detection of ambient scene light above a selectlevel or a low scene light signal responsive to the detection of ambientscene light below said select level and wherein said control meansoperates when said scene brightness means provides said low scene lightsignal to provide said quench signal upon the detection and integrationof substantially more scene light than is required to provide saidquench signal when said scene brightness means provides said high scenelight signal.
 10. The photographic camera of claim 9 including means forassuring that the spectral characteristics of the scene light incidentto said first photoresponsive element is different from the spectralcharacteristics of the scene light incident to said secondphotoresponsive element.